lacina206
幼苗
共回答了16个问题采纳率：100% 举报
10X是底数,真数是什么?
lgX + 2log10X(X) = 2
lgX + 2(lgX/lg10X) = 2
lgX + 2lgX/lg10X = 2
lg10XlgX + 2lgX = 2lg10X
(lg10+lgX)lgX+2lgX=2(lg10+lgX)
lgX+(lgX)^2 + 2lgX=2+2lgX
(lgX)^2 + lgX-2 = 0
(lgX+2)(lgX-1) = 0
lgX=-2,X=10^(-2)
lgX=1,X=10
1年前
10
